Fan and cooling apparatus

ABSTRACT

Holding arms of a frame member of a fan F are provided so as to project in the axial direction and so as to project outward from both sides of a housing in a direction orthogonal to the axial direction. Retaining projections are provided on the inner side in the front/rear direction at the tips in the axial direction extended outward from both sides of the housing, in the holding arms. The retaining projections are provided at the tips in the axial direction extended outward from both sides of the housing, of the holding arms, and positioned so that other parts in the frame member do not exist in the axial direction of the retaining projections.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a fan having holding arms to be attached to a heat sink, a cooling apparatus in which the fan is attached to a heat sink, a molding die assembly for molding a frame member as a component of the fan, and a method of manufacturing a frame member by using the molding die assembly.

2. Description of the Related Art

A typical CPU or an MPU installed in a computer generates much heat during operation, and has to be cooled to be kept in a predetermined temperature range. A cooling apparatus in which a fan is attached to a heat sink is used for the purpose. In this case, the fan has holding arms to be attached to a heatsink.

For example, there is a cooling fan of a cooling apparatus in which holding arms of a fan housing are provided so as to face each other in a predetermined direction orthogonal to the axial direction of a fan, and the holding arms are provided so as to project in parallel in the axial direction of the fan. At the tip of each of the holding arms, on the inner side in the predetermined direction, a retaining projection to be retained from the outside to the inside is provided in a corresponding position in a heat sink.

However, retaining to the inner side in the predetermined direction to the heat sink by the retaining projection in the holding arm in this case is performed in a position projected from the fan housing in the axial direction, so that stability of attachment of the fan to the heat sink is not always sufficient.

In order to mold a fan housing including a holding arm having a retaining projection by using a molding die assembly, for example, in a die releasing process, not only a die that is moved in the axial direction but also a die that is moved in the direction orthogonal to the axial direction are necessary, so that the molding die assembly has a complicated configuration. Due to this, the manufacturing cost of a fan and a cooling apparatus in which a fan is attached to a heat sink is high, and it cannot be said that manufacturing efficiency such as manufacturing speed is high. In the case of forming a retaining projection only by a die that is moved in the axial direction, an elongated pin-shaped part for forming the top face of the retaining projection is provided for the die, and a hole through which the die of the pin-shaped part passes is formed on the upper side in the axial direction of the retaining projection in the fan housing. The die therefore has drawbacks that the pin-shaped part is easily broken and the die life is short. The fan housing has a drawback that the strength of a base portion of the holding arm is low due to the hole.

BRIEF SUMMARY OF INVENTION

A fan of the present invention is characteristic in the shape of holding arms and the position where the retaining portion is formed.

The retaining portions are formed at the end of the holding arms and project from one arm toward the other arm. This feature reduces the width of fan and is favorable for installing the fan into a limited space. The arm with a projection, however, is often difficult to mold because the projection becomes an obstacle to remove a die.

The holding arms of the present invention extend parallel to the rotation axis of the impeller. It means that the die placed between the holding arms can be removed by sliding the die along the rotation axis if the die is not stumbled by the projection of the retaining portion.

The die of the present invention successfully avoids stumbling by forming the projection outside the imaginary surrounding wall, which is the extension along the rotation direction of the outer periphery of the housing. A die at the place of the projection can be moved toward housing along the rotation direction whereas a die at the place below the housing can be moved along a direction opposite toward the housing.

Thus, the fan can be manufactured while avoiding complication of the configuration of a molding die assembly, and reduction in the manufacturing cost and improvements in the manufacture efficiency such as manufacturing speed can be realized.

Other features, elements, steps, advantages and characteristics of the present invention will become more apparent from the following detailed description of preferred embodiments thereof with reference to the attached drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view.

FIG. 2 is a perspective view of a frame member of a fan.

FIG. 3 is a perspective view of a frame member of a fan.

FIG. 4 is a perspective view of a frame member of a fan.

FIG. 5 is a front view.

FIG. 6 is a side view.

FIG. 7 is a plan view.

FIG. 8 is a bottom view.

FIG. 9 is a schematic view of a die for injection molding.

DETAILED DESCRIPTION OF INVENTION

An embodiment of the present invention will be described with reference to the drawings.

FIGS. 1 to 6 show a cooling apparatus as an embodiment of the present invention. FIG. 1 is a perspective view, FIG. 2, FIG. 3, and FIG. 4 are perspective views of a frame member of a fan, FIG. 5 is a front view, FIG. 6 is a side view, FIG. 7 is a plan view, and FIG. 8 is a bottom view.

The cooling apparatus is used for cooling a CPU and an MPU and includes a heat sink H (attachment object) and an axial fan F for cooling the heat sink H. The cooling apparatus of the invention can be used for cooling devices other than the CPU and the MPU. The fan of the present invention can be also attached to an attachment object other than the heat sink and used.

In the heat sink H, a number of radiator fins 12 are arranged upright in parallel on a base 10. The heat sink H is made of a material having high thermal conductivity. The base 10 has a square shape in plan view and has support legs 14 for fixing the heat sink H (cooling apparatus) to a board to which the CPU and the MPU are attached. The heat sink H is fixed so that the under face of the base 10 is joined to predetermined parts of the CPU and the MPU and the heat of the CPU and the MPU can be conducted efficiently.

The fan F has, mainly, a frame member 20, a motor (driving mechanism) 60, and an impeller 70. The frame member 20 and the impeller 70 are made of a plastic material.

The frame member 20 has a housing 30 and holding arms 40 (including retaining projections 42). As shown in the schematic view of FIG. 9, the frame member 20 is integrally molded in the cavity of a die M for injection molding constructed by a first die piece M1 and a second die piece M2. In a releasing process of releasing the molding die assembly M from the cavity in the die, the frame member 20 has a shape so that it can be released from the die without substantial deformation by separating the first and second die pieces M1 and M2 from each other in the axial directions. The invention may use other means such as pulling means other than the means for moving the first and second die pieces M1 and M2 at the time of actual mold release.

The housing 30 includes a housing cylindrical part 32 having an almost circular inner peripheral surface, a motor supporting part 34 for supporting the motor 60 in a center portion on the suction port side (the upper side in FIGS. 1 and 5) of the housing cylindrical part 32, beams 36 supporting the motor supporting part 34 by connecting the motor supporting part 34 to the housing cylindrical part 32, and housing extension part 37 which extends outwardly from the housing cylindrical part 32 and defines the outer periphery 38 of the housing 30.

A hub 72 of the impeller 70 is fixed to a rotor in the motor 60. When the rotor rotates via a bearing mechanism, the hub 72 and blades 74 attached to the periphery of the hub 72 rotate, thereby blowing air to a discharge port side (lower side in FIGS. 1 and 5). A lead 62 having a connector at its end is led from the motor 60.

The holding arms 40 are provided to attach the fan F to the heat sink H. The holding arm 40 has a plate shape extending from the periphery of the housing 30 and along the axial direction and the horizontal direction. A pair of holding arms 40 is provided on each of the front and rear sides of the housing 30 (one of sides in the front/rear direction as a predetermined direction orthogonal to the axial direction of the housing 30 and the other side). The holding arms 40 are provided so as to extend to the discharge port side in the axial direction (predetermined direction) of the housing 30 as the axial direction of the fan F and project outward on both sides from the housing 30 in the direction orthogonal to the axial direction of the housing 30 (the horizontal direction orthogonal to also the predetermined direction), and are tapered while being inclined outward in the lateral direction to the bottom side in FIGS. 1 and 5. On the inside in the front/rear direction of each of the holding arms 40, a reinforcing rib 40 a is provided along the axial direction. The reinforcing rib 40 a prevents distortion at the time of molding and also reinforces after the molding.

The holding arm 40 does not always have to be linearly inclined and projected. For example, the holding arm 40 may have a shape which projects outward by being curved or bent.

The retaining projection 42 is provided on the inside in the front/rear direction at each of the tips in the axial direction projected outward from both sides of the housing 30 in the lateral direction. The fan F is attached to the heat sink H so as to surround the group of the radiator fins 12 by four holding arms 40. The discharge port side of the impeller 70 is positioned above the group of the radiator fins 12 of the heat sink H and the group of the radiator fins 12 is mainly cooled by the air blown to the discharge port side by rotation of the impeller 70. A pair of the retaining projections 42 is positioned on the front side and a pair of the retaining projections 42 is positioned on the back side. The retaining projections 42 are retained at the bottom sides of the four corners (retained parts) of the base 10 of the heat sink H. Since the retaining projections 42 of the holding arms 40 can be retained inward in the front/rear directions by the heat sink H in the positions projected outward from both sides of the housing 30 in the horizontal direction, stability of attachment of the fan F to the heat sink H can be increased.

The retaining projections 42 are provided at the tips in the axial direction projected outward from both sides of the housing 30 in the horizontal direction of the holding arms 40, and are positioned so that other parts in the frame member 20 do not exist in the axial direction of the retaining projections 42 (the axial direction is the vertical direction in FIGS. 1 to 5, that is, the vertical direction indicated by the alternate long and short dash line A for the retaining projection 42 in FIG. 2. In FIG. 2, the alternate long and short dash lines A are shown for only two retaining projections 42 out of the four retaining projections 42, but the directions of the other two retaining projections 42 are the same). Therefore, other parts of the frame member 20 do not exist via a space (a recess, a gap, a hole, or other spaces) in the axial direction of the retaining projections 42 (that is, the top face of each of the retaining projections 42 can be seen when the frame member 20 is seen from above in the axial direction).

FIGS. 3 and 4 explain the above described position of the retaining projection more precisely using the notion of imaginary planes 39 a and an imaginary surrounding wall 39 b. The imaginary planes 39 a extend parallel to the rotational axis of the impeller and include a part of the outer periphery 38 of the housing 30 thereon. The holding arm 40 extends on the imaginary planes to the one direction along the rotational axis. The holding arm may have a shape which projects outward by being curved or bent if it is on the imaginary plane. The imaginary surrounding wall 39 b extends along the rotational axis, including the outer periphery 38 thereon, and has the same shape of cross sectional profiles at right angle to the rotational axis as the shape of the outer periphery 38 at any point in the axial direction. The retaining portion should be formed outside the imaginary surrounding wall and between the imaginary planes.

With the configuration, the whole frame member 20 including the retaining projections 42 can be formed in the shape which can be released from the die without any substantial deformation by separating the first and second die pieces M1 and M2 from each other in the axial direction. Therefore, the frame member 20 can be manufactured while avoiding complication of the configuration of the molding die assembly M, so that reduction in the manufacturing cost of the fan F and improvements in manufacturing efficiency such as manufacturing speed can be realized. Molding of the retaining projections 42 can be realized by relatively thick parts of the molding die assembly M, and it is unnecessary to provide an elongated pin portion in, for example, the first die piece M1. It prevents the molding die assembly M from being damaged by breakage of the pin-shaped part, so that the life of the molding die assembly M can be increased. Since a through hole for molding the retaining projection 42 is not formed in the frame member 20, the strength in the base portion (the upper portion in FIGS. 1 to 5) of the holding arms 40 in the frame member 42 does not deteriorate.

Moreover, the retaining projections 42 are provided on the inside in the front/rear directions of the holding arms 40. Therefore, the intervals between the holding arms 40 are wider than those of the retaining projections 42 in the front/rear direction as the predetermined direction orthogonal to the axial direction. Consequently, by increasing the width as much as possible in the predetermined direction of the portion to be cooled in the heat sink H by gaseous flow on the discharge port side generated by the axial fan F among the holding arms 40, the cooling effect can be increased as much as possible.

In the embodiment, a tapped hole (fixing portion) for fixing the heat sink H (attachment object) to an object to be used is provided for the base 10. In such a case, however, in the direction orthogonal to the axial direction of the housing 30 of the fan F, tapped holes are provided between portions on both sides projected to the outside of the housing 30 in the front/rear direction in the holding arms 40. Since the tapped holes are open as shown in FIG. 7, the fan F does not become almost a barrier in the axial direction, so that it is preferable from the viewpoint of fixing work.

The positional relations in the vertical direction in the above description of the embodiment are simply for convenience of description based on the diagrams, but do not limit actual use states and the like.

The material of the frame member in the invention is not limited to plastic. A material which can form the frame member by the molding die assembly M and does not hinder the effects of the invention can be used. The invention does not preclude materials other than the molding materials as materials of the frame member like in the case of forming a predetermined material by insert molding.

In the invention, one or a plurality of holding arm(s) 40 can be provided on each of the sides in a predetermined direction orthogonal to the predetermined direction, of the housing 30. The invention is not limited to the embodiment in which a pair of holding arms is provided on each of the sides.

Further, the form of the heat sink H is not limited to the above. A form which is suitably cooled by the fan F (not necessarily by a discharge but by suction) can be properly employed.

The retaining projections of the holding arms to the heat sink are not necessarily retained at the four corners of the base but may be retained in other parts such as a part of the radiator fin. The retaining projection may be retained in a recess, a projection, or the like.

As described above, the fan of the invention has the configuration such that a pair of holding arms for attaching the fan to an attachment object extends from the periphery of an expanded portion of the housing to one side in the axial direction and at least part of the holding arms is in a position with longer distance from the rotary axis than the periphery of the expanded portion.

The retaining projection projects from one side of the holding arm to the other side and is in a position with longer distance from the rotary axis than the outer periphery of the expanded portion of the housing.

Consequently, the retaining projection of the holding arm can be retained to the attachment object in a position projected from one side of the holding arm to the other side, so that stability of attachment of the fan to the attachment object can be increased.

Preferably, in the fan of the present invention, the housing, the holding arms, and the retaining projections are formed integrally in the cavity of a molding die assembly constructed by a plurality of die pieces, and the die pieces can be released without any substantial deformation by separating part of the die pieces from the other die piece in a predetermined direction.

The “predetermined direction” in this case is a direction in which part of the die pieces (for example, when the molding die assembly is constructed by two die pieces, one of the die pieces and, when the molding die assembly is constructed by three or more die pieces, one or more die pieces out of the three or more die pieces) is separated from the other die piece(s), thereby enabling the housing, the holding arms, and the retaining projections integrally molded in the cavity of the molding die assembly can be released without any substantial deformation. The die piece may have any shape, size, and the like.

The retaining projection projects from one side toward the other side of the holding arm which extends from the outer periphery of the expanded portion of the housing to one side in the axial direction and at least part of the holding arm is in a position in a larger distance from the rotary axis than the outer periphery of the expanded portion. The retaining projection has a shape that it can be released from the die without any substantial deformation by separating part of the die pieces, which is in a position in a larger distance from the rotary shaft than the outer periphery of the expanded portion, from the other die pieces.

Thus, a fan including a holding arm having a retaining projection to be attached to an attachment object can be manufactured while avoiding complication of the configuration of a molding die assembly, and reduction in the manufacturing cost of the fan and improvements in the manufacture efficiency such as manufacturing speed can be realized.

Since the holding arm has the retaining projection which is projected from one side to the other side of the holding arm and is in a position in larger distance from the rotation axis than the outer periphery of the expanded portion, the interval between the holding arms is larger than the interval between the retaining projections in a predetermined direction.

The fan of the present invention may be an axial fan.

In this case, the interval between the holding arms is wider than the interval between the retaining projections in a direction with larger distance from the rotation axis, the width in a predetermined direction between the holding arms in which air is blown by the axial fan using a predetermined direction as the axial direction can be increased as much as possible.

The cooling apparatus of the present invention includes a heat sink and the above-described fan for cooling the heat sink. The heat sink has a fastening portion capable of retaining the retaining projection of the fan, and the fan is attached to the heat sink in a state where the retaining projection is retained by the fastening portion.

Since the housing including the holding arm extending from one side to the other side of the holding arm to be attached to the heat sink, the holding arm, and the retaining projection among the components of the fan can be manufactured while avoiding complication of the configuration of a molding die assembly, reduction in the manufacturing cost of the cooling apparatus in which the fan is attached to the heat sink in a state where the retaining projection of the holding arm of the fan is retained by the fastening portion of the heat sink and improvements in the manufacture efficiency such as manufacturing speed can be realized.

Since the interval between the holding arms is wider than the interval between the retaining projections in a direction with larger distance from the rotation axis, the width in a predetermined direction of a portion in which the heat sink is cooled by the air blown from the axial fan is increased as much as possible between the holding arms, and the cooling effect can be increased as much as possible.

A molding die assembly of the present invention is made by a plurality of die pieces having a cavity in which the housing, the holding arms, and the retaining projections can be integrally formed, and the housing, the holding arms, and the retaining projections can be released from the molding die assembly without any substantial deformation by separating a part of the die pieces from the other die pieces in the predetermined direction. With the molding die assembly, reduction in the manufacturing cost of the fan and improvements in manufacturing efficiency such as manufacturing speed can be realized. Since it is unnecessary to provide an elongated pin-shaped part for forming the fastening portion, the die is prevented from being damaged by breakage of the pin-shaped part, the life of the die can be increased.

A fan manufacturing method of the present invention includes: a molding step of integrally molding a housing, holding arms, and retaining projections in a cavity of the molding die assembly; and a die releasing step of releasing the housing, holding arms, and the retaining projections from the die without any substantial deformation by separating part of the die pieces constructing the molding die assembly from the other die pieces in the predetermined direction. According to the manufacturing method, reduction in the manufacturing cost of the fan and improvements in manufacturing efficiency such as manufacturing speed can be realized.

While the present invention has been described with respect to preferred embodiments, it will be apparent to those skilled in the art that the disclosed invention may be modified in numerous ways and may assume many embodiments other than those specifically set out and described above. Accordingly, it is intended by the appended claims to cover all modifications of the present invention which fall within the true spirit and scope of the invention. 

1. A fan comprising: an impeller; a driving mechanism for rotating the impeller; a housing rotatably supporting the impeller via a bearing mechanism and having an outer periphery that surrounds the impeller; a pair of holding arms which extend from outer periphery of the housing to one side in the axial direction, each arm extending on a respective imaginary plane which is parallel to a rotation axis of the impeller, at least a part of the arm reaching the radially outside of an imaginary surrounding wall which extends along the rotation axis and has the same shape of cross sectional profiles at right angle to the rotational axis as the shape of the outer periphery of the housing at any point in the axial direction and includes the outer periphery of the housing thereon; and a retaining portion projecting from one of the pair of holding arms toward the other, being situated radially outside area of the imaginary surrounding wall; wherein: the housing, the holding arms and the retaining portion are formed as a seamless one part in a cavity inside of a molding die assembly by injection molding of resin material; and the fan is axial flow type.
 2. A fan according to claim 1, wherein a process of releasing the seamless one part from the molding die assembly comprises a step of separating a die from the molding die assembly, the step in which the die is moving in parallel to the imaginary plane.
 3. A fan according to claim 2, wherein in the step of separating a die from the molding die assembly, the die is moving toward the other side in the axial direction.
 4. A cooling apparatus for cooling a electronic component, comprising: a heatsink; and an axial flow fan according to claim 1 for cooling the heat sink; wherein the heatsink has a fastening portion positioned such that the fastening portion can be mate to the retaining portion of the housing when the fan is placed at certain position relative to the heatsink.
 5. A cooling apparatus for cooling a electronic component, comprising: a heatsink; and an axial flow fan according to claim 2 for cooling the heat sink; wherein the heatsink has a fastening portion positioned such that the fastening portion can be mate to the retaining portion of the housing when the fan is placed at certain position relative to the heatsink.
 6. A cooling apparatus for cooling a electronic component, comprising: a heatsink; and an axial flow fan according to claim 3 for cooling the heat sink; wherein the heatsink has a fastening portion positioned such that the fastening portion can be mate to the retaining portion of the housing when the fan is placed at certain position relative to the heatsink. 